According to the Jamaica Center BID:
Originally erected in 1900 and located at 161-11 Jamaica Avenue, this is a fine example of a virtually extinct street amenity, and was designated a New York City landmark in 1981. It is double-faced with a cast-iron paneled base, fluted column post, and splendid acroteria motif crowning the clock face. It was restored [and] moved to its present location on Union Hall Street in 1989.